package com.lagou.sqlSession;

import com.lagou.config.BoundSql;
import com.lagou.pojo.Configuration;
import com.lagou.pojo.MappedStatement;
import com.lagou.utils.GenericTokenParser;
import com.lagou.utils.ParameterMapping;
import com.lagou.utils.ParameterMappingTokenHandler;
import com.lagou.utils.TokenHandler;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.*;
import java.util.ArrayList;
import java.util.List;

/**
 * @author HZF
 * @date 2020/4/2220:57
 * description
 */
public class SimpleExecutor implements Executor {
    @Override
    public <E> List<E> query(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        //1、注册驱动，获取连接
        Connection connection = configuration.getDataSource().getConnection();

        //2、获取SQL语句 select * from user where id = #{id} and username = #{username}
        //转换SQL语句：  select * from user where id = ?   and  username = ? ,转换的过程中，还需要对#{}立面的值进行解析存储
        String sql = mappedStatement.getId();
        BoundSql boundSql = getBoundSql(sql);

        //3、获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());

        // 4、设置参数
        //参数的全路径
        String paramterType = mappedStatement.getResultType();
        Class<?> parameterClass = getClassType(paramterType);
        
        List<ParameterMapping> parameterMappingsList = boundSql.getParameterMappingsList();
        for (int i = 0; i < parameterMappingsList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingsList.get(i);
            String content = parameterMapping.getContent();
            
            //使用反射根据参数名称获取对象值
            Field declaredField = parameterClass.getDeclaredField(content);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);


        }

        //5、执行SQL
        ResultSet resultSet = preparedStatement.executeQuery();
        String resultType = mappedStatement.getResultType();
        Class<?> resultTypeClass = getClassType(resultType);

        ArrayList<Object> objects = new ArrayList<>();



        //6、封装返回结果集
        while (resultSet.next()){
            Object o = resultTypeClass.newInstance();
            ResultSetMetaData metaData = resultSet.getMetaData();
            for (int i = 0; i < metaData.getColumnCount(); i++) {
                //字段名
                String columnName = metaData.getColumnName(i);
                //字段值
                Object value = resultSet.getObject(columnName);

                //使用反射根据数据库表和实体的对应关系，完成封装
                PropertyDescriptor propertyDescriptor = new PropertyDescriptor(columnName, resultTypeClass);
                Method writeMethod = propertyDescriptor.getWriteMethod();
                writeMethod.invoke(o,value);

            }
            objects.add(o);
        }
        return (List<E>) objects;


    }

    @Override
    public boolean update(Configuration configuration,MappedStatement mappedStatement, Object... params) throws Exception {
        Connection connection = configuration.getDataSource().getConnection();
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        String parameterType = mappedStatement.getParameterType();
        Class<?> parameterClass = getClassType(parameterType);
        List<ParameterMapping> parameterMappingsList1 = boundSql.getParameterMappingsList();
        for (int i = 0; i < parameterMappingsList1.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingsList1.get(i);
            String content = parameterMapping.getContent();
            //使用反射根据参数名称获取对象值
            Field declaredField = parameterClass.getDeclaredField(content);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }
        boolean execute = preparedStatement.execute();
        return execute;
    }

    @Override
    public boolean delete(Configuration configuration, MappedStatement mappedStatement, Object... params) throws Exception {
        Connection connection = configuration.getDataSource().getConnection();
        //2、获取SQL语句
        //转换SQL语句：delete from user where id = ?,转换的过程中，还需要对#{}立面的值进行解析存储
        String sql = mappedStatement.getSql();
        BoundSql boundSql = getBoundSql(sql);
        //3、获取预处理对象：preparedStatement
        PreparedStatement preparedStatement = connection.prepareStatement(boundSql.getSqlText());
        // 4、设置参数
        //参数的全路径
        String paramterType = mappedStatement.getParameterType();


        Class<?> parameterClass = getClassType(paramterType);

        List<ParameterMapping> parameterMappingsList = boundSql.getParameterMappingsList();
        for (int i = 0; i < parameterMappingsList.size(); i++) {
            ParameterMapping parameterMapping = parameterMappingsList.get(i);
            String content = parameterMapping.getContent();
            //使用反射根据参数名称获取对象值
            Field declaredField = parameterClass.getDeclaredField(content);
            //设置暴力访问
            declaredField.setAccessible(true);
            Object o = declaredField.get(params[0]);
            preparedStatement.setObject(i+1,o);
        }
        //5、执行SQL
        boolean execute = preparedStatement.execute();
        return execute;
    }

    private Class<?> getClassType(String paramterType) throws ClassNotFoundException {
        if(paramterType!=null){
            Class<?> aClass = Class.forName(paramterType);
            return aClass;
        }
        return  null;
    }

    /**
     * 对#{}的解析工作 1、将#{}用？ 代替， 2、解析出#{}立面的值进行存储
     * @param sql
     * @return
     */
    private BoundSql getBoundSql(String sql) {
        ParameterMappingTokenHandler parameterMappingTokenHandler = new ParameterMappingTokenHandler();
        GenericTokenParser genericTokenParser = new GenericTokenParser("#{", "}", parameterMappingTokenHandler);
        //解析出来的SQL
        String parseSql = genericTokenParser.parse(sql);
        //#{}里面解析出来的参数名称
        List<ParameterMapping> parameterMappings = parameterMappingTokenHandler.getParameterMappings();

        BoundSql boundSql = new BoundSql(parseSql,parameterMappings);


        return boundSql;
    }
}
